It's like the difference between quiet supporters and active allies in the ongoing challenges over systemic discrimination based on race.
I have a diagram of the continuum of climate change denial to alarmism that I've been using since I created it in 2016 (embedded in this article - https://medium.com/the-future-is-electric/climate-change-deniers-are-increasingly-angry-and-hostile-52b32b0e6896) but you might want to take the racism scale (I prefer the first incarnation as it's more communicative) and craft a variant for deniers that includes your soft deniers.